Does XML allow you to define for-loops inside <bracketed> items then reference the loop variables inside {{template vars}}? https://youtu.be/b9WDcFsKixo?t=223
I guess it doesn't prevent you from doing such things, but... well... there's some eyebrow-raising shoehorning in this one.
Yes it does. Apache ant did that... many many years ago.
Creating a new language that looks like XML but is not XML is... kind of unforgivable. I'd go as far and call it amateur-like. We already have good configuration languages (such as dhall-lang) and when more power is needed, then just use a real language and provide a DSL inside of it.